Communication system and method for discovering end-points that utilize a link layer connection in a wired/wireless local area network

ABSTRACT

Aspects of the invention provide a communication system and method in a hybrid wired/wireless local area network. At least one discovery message may be broadcasted to at least one of a plurality of access points. A response may be received from one or more of the access points. The response may report a presence of at least one access device located within a coverage area of one or more of the access points. A status of at least one access device located within a coverage area of one or more of the access points may be requested from the access points.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

The present U.S. Utility patent application claims priority pursuant to35 U.S.C. §120, as a continuation, to the following U.S. Utility patentapplication which is hereby incorporated herein by reference in itsentirety and made part of the present U.S. Utility patent applicationfor all purposes:

U.S. Utility application Ser. No. 10/606,503, entitled “CommunicationSystem and Method for Discovering End Points that Utilize a Link LayerConnection in a Wired/Wireless Local Area Network (Attorney Docket No.BP2612), filed Jun. 26, 2003, pending, which claims priority pursuant to35 U.S.C. §119(e) to the following U.S. Provisional patent applicationswhich are hereby incorporated herein by reference in their entirety andmade part of the present U.S. Utility patent application for allpurposes:

a. U.S. Provisional Patent Application Ser. No. 60/411,261 entitled“Communications Systems Software and Protocols” filed on Sep. 17, 2002;

b. U.S. Provisional Patent Application Ser. No. 60/411,301 entitled“Method and System for Providing a Scalable Integrated Switch andWireless Architecture” filed on Sep. 17, 2002; and

c. U.S. Provisional Application Ser. No. 60/435,984 entitled“Communication System and Method in a Wireless Local Area Network” filedon Dec. 20, 2002.

The above stated applications are all incorporated herein by referencein their entirety.

BACKGROUND OF THE INVENTION

Embodiments of the present application relate generally to local areanetworks, and more particularly to a communication method and system ina hybrid wired/wireless local area network (WLAN).

The Open Systems Interconnection (OSI) model promulgated by theInternational standards organization (ISO) was developed to establishstandardization for linking heterogeneous computer and communicationsystems. The OSI model describes the flow of information from a softwareapplication of a first computer system to a software application of asecond computer system through a network medium. FIG. 1 a is a blockdiagram 100 of the OSI model. Referring to FIG. 1 a, the OSI model hasseven distinct functional layers including layer 7, an application layer114; layer 6, a presentation layer 112; layer 5, a session layer 110;layer 4, a transport layer 108, layer 3, a network layer 106; layer 2: adata link layer 104; and layer 1, a physical layer 102. The physicallayer 102 may further include a physical layer convergence procedure(PLCP) sublayer 102 b and a physical media dependent sublayer 102 a. Thedata link layer 104 may also include a Medium access control (MAC) layer104 a.

In general, each OSI layer describes certain tasks which are necessaryfor facilitating the transfer of information through interfacing layersand ultimately through the network. Notwithstanding, the OSI model doesnot describe any particular implementation of the various layers. OSIlayers 1 to 4 generally handle network control and data transmission andreception, generally referred to as end-to-end network services. Layers5 to 7 handle application issues, generally referred to as applicationservices. Specific functions of each layer may vary depending on factorssuch as protocol and/or interface requirements or specifications thatare necessary for implementation of a particular layer. For example, theEthernet protocol may provide collision detection and carrier sensing inthe physical layer. Layer 1, the physical layer 102, is responsible forhandling all electrical, optical, opto-electrical and mechanicalrequirements for interfacing to the communication media. Notably, thephysical layer 102 may facilitate the transfer of electrical signalsrepresenting an information bitstream. The physical layer 102 may alsoprovide services such as, encoding, decoding, synchronization, clockdata recovery, and transmission and reception of bit streams.

The PLCP layer 102 b may be configured to adapt and map servicesprovided by the physical layer 102 to the functions provided by thedevice specific PMD sublayer 102 a. Specifically, the PLCP layer 102 bmay be adapted to map PHY sublayer service data units (PDSUs) into asuitable packet and/or framing format necessary for providingcommunication services between two or more entities communicating viathe physical medium. The PMD layer 102 a specifies the actualmethodology and/or protocols which may be used for receiving andtransmitting via the physical medium. The MAC sublayer 104 a may beadapted to provide, for example, any necessary drivers which may beutilized to access the functions and services provided by the PLCPsublayer 102 b. Accordingly, higher layer services may be adapted toutilize the services provided by the MAC sublayer 104 a with little orno dependence on the PMD sublayer 102 a.

802.11 is a suite of specifications promulgated by the Institute ofElectrical and Electronics Engineers (IEEE), which provide communicationstandards for the MAC and physical (PHY) layer of the OSI model. The801.11 standard also provides communication standards for wired andwireless local area networks (WLANs). More specifically, the 802.11standard specifies five (5) types of physical layers for WLANs. Theseinclude, frequency hopping spread spectrum (FHSS), direct sequencespread spectrum (DSSS), infrared (IR) communication, high rate directsequence spread spectrum spread spectrum (HR-DSS) and orthogonalfrequency division multiplexing (OFDM). The 802.11 standard alsoprovides a PLCP frame format for each of the specified PHY layers.

Over the past decade, demands for higher data rates to supportapplications such as streaming audio and streaming video, have seenEthernet speeds being increased from about 1-2 megabit per second(Mbps), to 10 Mbps, to 100 Mbps, to 1 gigabit per second (Gbps) to 10Gbps. Currently, there are a number of standards in the suite ofspecifications, namely 802.11b, 802.11a and 802.11g which have beenadapted to facilitate the demands for increased data rates. The 802.11gstandard for example, provides a maximum data rate of about 54 Mbps at atransmitter/receiver range of 19 meters (m) in a frequency range of 2.4GHz to 2.4835 GHz. The 802.11b standard for example, provides a maximumdata rate of about 11 Mbps at a transmitter/receiver range of 57 meters(m) in a frequency range of 2.4 GHz to 2.4835 GHz. Finally, the 802.11astandard for example, may be adapted to provide a maximum data rate ofabout 54 Mbps at a transmitter/receiver range of 12 meters (m) in a 300MHz segmented bandwidth ranging from 5.150 GHz to 5.350 GHz and from5.725 GHz to 5.825 GHz.

The 802.11 standard forms the basis of the other standards in the suiteof specifications, and the 802.11b, 802.11a and 802.11g standardsprovide various enhancements and new features to their predecessorstandards. Notwithstanding, there are certain elementary building blocksthat are common to all the standards in the suite of specifications. Forexample, all the standards in the suite of specifications utilize theEthernet protocol and utilize carrier sense multiple access withcollision avoidance (CSMA/CA) for distribution coordination function(DCF) and point coordination function (PCF).

CSMA/CA utilizes a simple negotiation scheme to permit access to acommunication medium. If a transmitting entity wishes to transmitinformation to a receiving entity, the transmitting entity may sense thecommunication medium for communication traffic. In a case where thecommunication medium is busy, the transmitting entity may desist frommaking a transmission and attempt transmission at a subsequent time. Ina case where the communication transmission is not busy, then thetransmitting entity may send information over the communication medium.Notwithstanding, there may be a case where two or more transmissionentities sense that the communication medium is not busy and attempttransmission at the same instant. To avoid collisions andretransmissions, CSMA/CA or a ready to send (RTS) and clear to send(CTS) messaging scheme is employed, for example. Accordingly, whenever atransmitting device senses that the communication medium is not busy,then the transmitting device may send a ready to send message to one ormore receiving device. Subsequent to the receipt of the ready to sendmessage, the receiving device may send a clear to send message. Uponreceipt of the clear to send message by the transmitting device, thetransmitting device may initiate transfer of data to the receivingdevice. Upon receiving packets or frames from the transmitting device,the receiving device may acknowledge the received frames.

The 802.11b standard, commonly called Wi-Fi, which represents wirelessfidelity, is backward compatible with its predecessor standard 802.11.Although 802.11 utilizes phase-shift keying (PSK) as a modulationscheme, 802.11b utilizes a hybrid PSK scheme called complementary codekeying (CCK). CCK permits higher data rate and particularly lesssusceptible to interference effects such as multipath-propagationinterference, the PSK.

The 802.11a standard provides wireless asynchronous transfer mode (ATM)support and is typically utilized in access hubs. 802.11a utilizesorthogonal frequency-division multiplexing (OFDM) modulation/encodingscheme, which provides a maximum data rate 54 Mbps. Orthogonalfrequency-division multiplexing is a digital modulation technique whichsplits a signal into several narrowband channels, with each channelhaving a different frequency. Each narrowband channel is arranged so asto minimize the effects of crosstalk between the channels and symbols inthe data stream.

Since equipment designed to provide support for 802.11a operates atfrequencies in the ranges 5.150 GHz to 5.350 GHz and from 5.725 GHz to5.825 GHz, 802.11a equipment will not interoperate with equipmentdesigned to operate with the 802.11b standard which defines operation inthe 2.4 to 2.4835 GHz frequency band. One major drawback is thatcompanies that have invested in 802.11b equipment and infrastructure maynot readily upgrade their network without significant expenditure.

The 802.11g standard was developed as an extension to 802.11b standard.The 802.11g standard may utilize a similar OFDM modulation scheme as the802.11a standard and delivers speeds comparable with the 802.11astandard. Since 802.11g compatible equipment operates in the sameportion of the electromagnetic spectrum as 802.11b compatible equipment,802.11g is backwards compatible with existing 802.11b WLANinfrastructures. Due to backward compatibility of 802.11g with 802.11b,it would be desirable to have an 802.11b compliant radio card capable ofinterfacing directly with an 802.11g compliant access point and also an802.11g compliant radio card capable of interfacing directly with an802.11b compliant access point.

Furthermore although 802.11g compatible equipment operates in the 2.4GHz to 2.4835 GHz frequency range, a typical transmitted signal utilizesa bandwidth of approximately 22 MHz, about a third or 30% of the totalallocated bandwidth. This limits the number of non-overlapping channelsutilized by an 802.11g access point to three (3). A similar scenarioexists with 802.11b. Accordingly, many of the channel assignment andfrequency reuse schemes associated with the 802.11b standard may beinherent in the 802.11g.

RF interference may pose additional operational problems with 802.11band 802.11g equipment designed to operate in the 2.4 GHz portion of theelectromagnetic spectrum. The 2.4 GHz portion of the spectrum is anunlicensed region which has been utilized for some time and is crowdedwith potential interfering devices. Some of these devices includecordless telephone, microwave ovens, intercom systems and baby monitors.Other potential interfering devices may be Bluetooth devices.Accordingly, interference poses interference problems with the 802.11band 802.11g standards.

802.11a compatible equipment utilizes eight non-overlapping channels, ascompared to three non-overlapping channels utilized by 802.11b.Accordingly, 802.11a access points may be deployed in a more densemanner than, for example 802.11b compatible equipment. For example, upto twelve access points each having a different assigned frequency maybe deployed in a given area without causing co-channel interference.Consequently, 802.11a may be particularly useful in overcoming some ofthe problems associated with channel assignment, especially in areasthat may have a dense user population and where increased throughput maybe critical. Notwithstanding, the higher operating frequency of 802.11aalong with its shorter operating range, may significantly increasedeployment cost since a larger number of access points are required toservice a given service area.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with some aspects of the present invention asset forth in the remainder of the present application with reference tothe drawings.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to apparatus and methods of operationthat are further described in the following Brief Description of theDrawings, the Detailed Description of the Invention, and the claims.Other features and advantages of the present invention will becomeapparent from the following detailed description of the invention madewith reference to the accompanying drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 a is a block diagram of the OSI model.

FIG. 1 b is a block diagram illustrating a general PLCP frame as definedby 802.11.

FIG. 1 c is a block diagram illustrating a PLCP frame utilized byfrequency hopping spread spectrum as defined by 802.11.

FIG. 1 d is a block diagram illustrating a PLCP frame for directsequence spread spectrum and high rate direct sequence spread spectrumas defined by 802.11.

FIG. 1 e is a block diagram illustrating a PLCP frame for orthogonalfrequency division multiplexing as defined by 802.11.

FIG. 2 is a block diagram of an exemplary system for network managementin a wireless local area network in accordance with an embodiment of theinvention.

FIG. 3 is a block diagram of an exemplary Enterprise Wireless LAN havingswitches serving as the edge managers in accordance with an embodimentof the invention.

FIG. 4 is a block diagram of an exemplary hybrid wired/wireless networkwhich may be used to illustrate the discovery of access devices inaccordance with an aspect of the invention.

FIG. 5 is a high level block diagram of a exemplary message exchangethat may be used to discover an access device in accordance with anaspect of the invention.

FIG. 6 is a diagram illustrating an exemplary message exchange forlocating a wired client device using the messaging protocol inaccordance with an embodiment of the invention.

FIG. 7 is a block diagram of a server that may be adapted to discoverend-points in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Aspects of the invention provide a communication system and method in ahybrid wired/wireless local area network. At least one discovery messagemay be broadcasted to at least one of a plurality of access points. Aresponse may be received from one or more of the access points. Theresponse may report a presence of at least one access device locatedwithin a coverage area of one or more of the access points. A status ofat least one access device located within a coverage area of one or moreof the access points may subsequently be requested from the accesspoints.

FIG. 1 b is a block diagram 120 illustrating a general PLCP frame asdefined by 802.11. Referring to FIG. 1 b, there is shown preamble 122,PLCP header 124, MAC data 126, and CRC 128. Preamble 122 may includesynchronization (SYNC) data 122 a and synchronization delimiter 122 b.The PLCP header 124 may include, for example PLCP signal field (PSF) 124a, service data 124 b, length 124 c and other fields. The preamble 122may be dependent on the PHY. The SYNC data 122 a may include a uniquebit stream that may be adapted to signal timing parameters such as thestart of a frame. The SYNC data 122 a is used for bit synchronizationand demodulation. The SYNC delimiter 122 b provides frame timinginformation and may be adapted to delimit the end of synchronizationinformation. The PLCP header 124 may be adapted to contain informationused for decoding the frame. For example, the PSF 124 a may be adaptedto include communication data rate information. The service data 124 bis generally reserved, but may be utilized to provide applicationspecific functionality. The length 124 c may be adapted to indicate thelength of the MAC data 126. In this regard, the length 124 c may beexpressed in terms of the time required to transmit the MAC data 126.

FIG. 1 c is a block diagram 130 illustrating a PLCP frame utilized byfrequency hopping spread spectrum as defined by 802.11. Referring toFIG. 1 c, there is shown a SYNC data 132, PLCP header 134 and PSDU 136.The PLCP header 134 may include, for example, PSDU length word (PLW) 134a, PLCP signaling field (PSF) 134 b, header error check field or CRC 134c and other fields. The PLW 134 a may specify the number of octetscontained in the PSDU 136. The PSF 134 be may be 4-bits in length andmay be used to denote the communication data rate.

FIG. 1 d is a block diagram 140 illustrating a PLCP frame for directsequence spread spectrum and high rate direct sequence spread spectrum(HR-DSS) as defined by 802.11. Referring to FIG. 1 d, there is shownpreamble 142, PLCP header 144 and MPDU 146. Preamble 142 may includesynchronization (SYNC) data 142 a and synchronization delimiter 142 b.The PLCP header 144 may include PLCP signal field (PSF) 144 a, servicedata 144 b, length 144 c, and CRC field 144 d. The SYNC data 142 a maybe 128 bits as compared to 8 bits for SYNC data 132 a for frequencyhopping spread spectrum. The CRC 144 d is 16 bits, which is similar toCRC 134 c for frequency hopping spread spectrum.

FIG. 1 e is a block diagram 150 illustrating a PLCP frame for orthogonalfrequency division multiplexing as defined by 802.11. Referring to FIG.1 e, there is shown preamble 152, PLCP header 154 and PSDU 156, tail 158and pad 160. Preamble 152 may include synchronization (SYNC) data 152 aand synchronization delimiter 152 b. The PLCP header 154 may includelength 154 a, PLCP signal field (PSF) 154 b, reserved field 154 c,parity 154 d, tail 154 e and service 154 f. The length 154 a is a 12-bitfield that may be adapted to indicate the length of the frame. The PSF154 b is a 4-bit field that may indicate a modulation scheme utilizedand its associated coding rate of the PSDU. For example, thespecification utilizes binary 1011 to represent 6 Mbps, 1111 torepresent 9 Mbps, 1010 to represent 12 Mbps, 1110 to represent 18 Mbps,1001 to represent 24 Mbps, 1011 to represent 36 Mbps, 1000 to represent48 Mbps and finally, 1100 to represent the maximum standardized rate if54 Mbps. The reserved field 154 c is a 1 bit field that is reserved forfuture use and may be adapted for application specific use. The parityfield 154 d may indicate odd or even parity. The tail field 154 e is a6-bit field. The service field 154 f is a 16-bit field that may beadapted to indicate the type of service.

In a typical wireless local area network, especially as access devicesbecome mobile throughout the network, channel capacity may be rapidlytime varying. For example, when the distance from an access device to anaccess point increases or decreases due to mobility, the channelcapacity and ultimately the channel throughput may change with time. Inaccordance with an embodiment of the invention, a switch for example,may utilize the messaging protocol to facilitate communication betweenone or more of a plurality of access devices and/or access points,and/or other switches. The messaging protocol may be adapted to provide,for example, switch filter transfer, bandwidth management, sessioncontrol and management, load balancing and QoS control and management.

In for example, a hybrid wired/wireless in which bandwidth is rapidlychanging over time due to access device mobility, the messaging protocolin accordance with an aspect of the invention may be adapted to performbandwidth management for a wired and/or a wireless portion of thenetwork. The bandwidth management may include, but is not limited to,performing one or more tasks including, but not limited to, implementingpolicies, tracking bandwidth usage and adapting bandwidth allocation tomeet user demands and system capability. The management of these tasksmay pertain to providing mobility and operability throughout a hybridwired/wireless communications network.

FIG. 2 is a block diagram of an exemplary system for network managementin a wireless local area network in accordance with an embodiment of theinvention. Referring to FIG. 2, there is illustrated a first networkingdomain 214 and a second networking domain 234. The first networkingdomain 214 may include a switch 202, and access points 204, 206, 208,210, 212. Each of access points 204, 206, 208, 210, 212 may be coupledto the switch 202. The second networking domain 234 may include a switch222, and access points 224, 226, 228, 230, 232. Each of access points224, 226, 208, 230, 232 may be coupled to the switch 222. Switch 222 maybe coupled to switch 202 through any one or more of a wired and awireless medium. Although not shown, at least some of the access pointsin any one of the networking domains 214, 234 may be coupled to eachother. Notwithstanding, a plurality of actual and/or virtual channelsmay be provided to facilitate communication with the access points andswitches. Although the networking domains 214 and 234 are illustrated asseparate networking entities, the invention is not so limited.Accordingly, the networking domain 214, 234 may be part of a singlenetworking entity, but may represent separate security domains withinthe single networking entity.

In operation, any one or more of the access points in any one or more ofthe networking domains 214, 234 may be adapted to receive networkmanagement related information and parameters from one or more of theswitches 202, 222. In one embodiment of the invention, for example,access point 206 may be adapted to receive for example, bandwidthinformation from switch 202. Similarly, any one or more of access points204, 208, 210, 214 may receive network management related informationfrom switch 202. Similarly, any one or more of access points 224, 226,228, 230, 232 may receive network management related information fromswitch 222.

In another aspect of the invention, the switches 202, 222 may be adaptedto provide, for example, certain QoS management activities to the accesspoints using the messaging protocol in accordance with an aspect of theinvention. Accordingly, some activities such as bandwidth policing,bandwidth management, load balancing, roaming and handover may behandled by coordinating one or more switches and one or more accesspoints utilizing the messaging protocol in accordance with an embodimentof the invention. Notwithstanding, a switch for example 222, may beadapted to establish rules that may be adapted by the access points 224,226, 228, 230, 232 in carrying out these activities. The rules may bepropagated from the switches 222, 202 to the access points 204, 208,210, 214, 224, 226, 228, 230, 232 using the messaging protocol.Prioritization and processing, for example, may be based on acceptablelevels of latency and bandwidth availability. For example, an IPtelephone call may be assigned highest queuing and processing priorityin order to minimize latency. Policing, for example, may include taskswhich limit and control the usage of available bandwidth by a particularaccess device or a type of access device. All these tasks may becontrolled using the messaging protocol.

In accordance with an aspect of the invention, the messaging protocol(MP) may be utilized for communication by an access device in forexample, an enterprise Wireless LAN (WLAN), in order to provide servicessuch as enhanced WLAN service to access devices or mobile stations. Thecommunication, in addition to ordinary WLAN device communication such asauthentication, authorization, key exchanges, beacon broadcast, etc.,may provide additional features not provided by a WLAN to its clients.These additional features may include, but are not limited to, accesscontrol, load balancing, network management and quality of service.Enterprise WLAN devices that may utilize messaging protocol messagetransactions may include but are not limited to, wireless access points,enterprise switches, and wireless stations. These devices may be MPenabled in some instances.

In accordance with the invention, an exemplary WLAN Architecture may beprovided. In the enterprise Wireless LAN environment, the wirelessdevices may be located at the edge of the network. The wireless devicesmay be connected or coupled to the enterprise network via one or moreaccess points, which in turn may be the edge devices of, for example, awired LAN. The access points may be connected to the LAN via switches.These switches, called Wireless LAN Switches, in certain instances, donot only perform Layer 2 switching, but may be adapted to function as awireless edge manager. They may also provide additional functionalitieslike access control, firewall functions, traffic privacy and quality ofservice, network management, and load balancing.

FIG. 3 is a block diagram 300 of an exemplary Enterprise Wireless LANhaving switches serving as the edge managers in accordance with anembodiment of the invention. Referring to FIG. 3, there is shown, alocal area network (LAN) 302, authentication server 304, switches 306,308, access points (APs) 310, 312, 314, 316, 318, 320 and access devices322, 324, 326, 328, 330, 332, 334, 336, 338. It should be recognizedthat the invention is not limited to and Enterprise WLAN. The inventionmay be applicable to a wired LAN, a wireless LAN and any combinationthereof.

Wireless transmission or communication between the access devices orclients, and the access points may be secure. This may be also be truefor the wired connections between any of the access points 310, 312,314, 316, 318, 320 and the switches 306, 308. The switches 306, 308 andaccess points 310, 312, 314, 316, 318, 320 may be adapted to communicateusing, for example, an Ethernet protocol. From the switch's perspective,the switch may be switching regular layer 2 frames. Within the switch,knowledge of a WLAN and its management intelligence may reside primarilyin software.

The messaging protocol, in accordance with an aspect of the invention,may be adapted to utilize one or more protocols associated with a devicecommunication protocol (DCP) umbrella (DCPU). The messaging protocol maybe adapted to run over the transmission control protocol (TCP) or userdatagram protocol (UDP) protocols using for example, a well-known portnumber specified under the framework of the device communicationprotocol. Under the DCP umbrella, there may be several sub-protocolsdefined for the purpose of facilitating interoperability with otherproducts. Some of these products may include but are not limited to,cable modems and cable modem termination systems (CMTS) equipment. Themessaging protocol may be adapted to include the necessary protocolsunder DCP to facilitate communication for wired and/or WLAN devices.

DCP is a Layer 5 protocol. It may be adapted to use a default TCP/UDPport of for, example, 3188, which is a registered IETF port assignment.A DCP header, starting from the TCP/UDP payload, may have a 6-byteheader as follows:

Sub_Protocol RCM_MAGIC_NUMBER RCM_SubProtocol Specifics octets 0-3(=0x4252434d, or octets 4-5 Variant # octets “RCM”)

The RCM_SubProtocol field may indicate an officially registeredsub-protocol for other devices. Exemplary valid values may beillustrated in the following table:

RCM_SubProtocol Description 0x0000 Reserved 0x0001 Propane ControlProtocol (PCP) 0x0002 Inter-CMTS Communications Protocol (ICCP) 0x0003imPulse Mitigation Signaling Protocol (PMSP) 0x0004 Loadbox SignalingProtocol (LBSP) 0x0005 Propane Testing Protocol (PTP) 0xFFFE Reserved0xFFFF ReservedThe message protocol may be adapted to register for a next availablevalue for the RCM_SubProtocol. Message protocol specific information maybe adapted to start at the 6^(th) octet in the DCP packet, al though theinvention is not limited in this regard.

In accordance with an aspect of the invention, the messaging protocolmay be utilized for communication between various wireless networkingdevices and/or clients. In an embodiment of the invention, the messagingprotocol may be adapted to facilitate communication between variousaccess points 310, 312, 314, 316, 318, 320 and WLAN switches 306, 308.Information exchanged between these two devices may include, but is notlimited to, control, configuration and status information of the deviceor unit and client session information. The control information mayinclude, for example, signaling information that may be communicatedin-band or out-of-band. Such information may be exchanged in order toenable the six features mentioned in the previous section in the WLAN.

The messaging protocol may include a message type. The messagingprotocol may include, for example six (6) categories of messages ormessage types, although the invention is not so limited. These messagesand their usage may be illustrated as follows:

AP_Status: from AP to Switch or AP

-   -   An AP_Status message may be used to indicate, for example, an        access point capacity, bandwidth allocation, the number of        attached clients, signal strength, power levels, etc.

AP_Config: from Switch to AP

-   -   An AP_Config message may be used to configure an access point to        accommodate a client. This may include but is not limited to,        802.11e QoS, security information, etc.

Switch_Status: from Switch to Switch

-   -   A Switch_Status message may be used to indicate a switch's        association with clients, including the client's session        information, access control, QoS parameters, etc.

Switch_Config: from Switch to Switch

-   -   A Switch_Config message may be used to configure a WLAN Switch        to accommodate a client, including access control, QoS        configuration, etc.

Client_Status: from AP to Switch

-   -   A Client_Status message may be used to indicate a client's        information, including client identification, associated MAC        address, session status, connecting location, etc.

Device_Discovery: any device to any device

-   -   In a client-server model of network services, the        Device_Discovery message may be used by a server to discover        clients or by client to discover servers. The message may be        broadcast to some or all devices in the subnet to draw responses        from the intended devices.

In each of the message types above, the message may include, for examplefour (4) message subtypes—.request, .data, .alert, and .ack. A messagetype/subtype pair of .request and .data may represent the request ofdata and a corresponding response of data itself. The subtype pair of.alert and .ack may represent the voluntary transmission of data and itsacknowledgement. Additionally, there may be two conventions utilized ina message exchange sequence. Accordingly, if a message exchange sequencestarts with a request (.req), it may be followed by a reactivetransmission of data (.data). Similarly, if a message exchange sequencestarts with a proactive transmission of data (.alert), it is followed byan acknowledgement (.ack).

Since the message protocol may be a sub-protocol of DCP, a messagingprotocol message may have 6 octets at the front of the TCP/UDP Payloadidentifying it as a DCP packet. Starting from Octet 6 (O-based), at thebeginning of a DCP payload, or a messaging protocol message, 3 octetsmay be reserved to indicate the message type of a messaging protocolmessage. In accordance with an aspect of the invention, a filteringengine in the network may be adapted to filter certain types ofmessaging protocol messages by examining the three octets of a messagingprotocol message. In this regard, a messaging protocol messageidentification system may be implemented.

In accordance with an aspect of the invention, in a case where a messageprotocol (MP) message may be registered with a DCP sub-protocol valueof, for example 0x0006, a typical messaging protocol message, as acontinuation after the DCP header, may be as follows. Again, thebeginning of the DCP header is the first byte of the TCP or UDP payload.

MP MP Message Message Identifier Payload RCM_MAGIC_NUMBERRCM_SubProtocol (octets (variant # (octets 0-3) (octets 4-5) 6-8) bytes)0x4252434d (“RCM”) 0x0006 — —

The messaging protocol message identifier may specify a type ofmessaging protocol messages as addressed above. The messaging protocolmessage types may be enumerated in the following table.

value in first two octets of Message Type Message Identifier AP Status0x0001 AP Config 0x0002 Switch Status 0x0003 Switch Config 0x0004 ClientStatus 0x0005 Device Discovery 0x0006

The 3^(rd) byte of the messaging protocol message identifier mayidentify a sub-type of the messaging protocol Message. As addressedabove, a messaging protocol message may be a data requisition, a dataresponse, a data alert or an acknowledgement. The assigned values aregiven in the following table.

value in third octet of Message Message Sub-type Identifier data request(.req) 0x01 data response (.data) 0x02 data alert (.alert) 0x03acknowledgement (.ack) 0x04

The messaging protocol message payload may be ASCII-based, similar toother IETF protocols such as, real-time streaming protocol (RTSP),hyper-text transport protocol (HTTP), session initiation protocol (SIP),etc. With an ASCII-based protocol, the parameters to be exchangedbetween devices may be formatted as follows:

<field{.subfield}>: <field value>

It should be recognized that the invention is not limited to thearrangement of the parameters as shown. Notwithstanding, a messagingprotocol message in ASCII format may be recognized by inspection.Notably, the messaging protocol message format provides flexibility, inthat future revision may be possible by adding new fields.

In accordance with an aspect of the invention, exemplary valid fieldsand subfields in a messaging protocol message may be as follows:

Field Subfields Descriptions Transaction_ID — a unique ID identifyingthe request/data sequence or data/ack sequence Session ID a unique IDidentifying an association session that the wireless user engaged to theWLAN, this may be a Wireless Laptop logging in, a powered on WirelessVOIP phone, a Wireless PCS, etc. Switch_ID the WLAN switch that governsthis session AP_ID the AP associated with this session Client_MAC theclient MAC address Status status of a session, whether the wirelessstation is connected to the network, disconnected from the network, orno traffic has been transmitted in this session; from an AP'sperspective, it may be associated or disassociated with the sessionStatus_Duration the time-duration that has reached the status Passwordpassword that allows a client station to join the network Access_Levellevel of access allowed for this client session Access_Duration Durationof access allowed Access_Start_TOD TOD that access may beginAccess_End_TOD TOD that access must end Signal the signal strength ofthe wireless station received; strongest possible signal = 100 DeviceType Device type; in the WLAN architecture, it may be all permissibledevices, like a switch, an AP, a laptop, a phone, a PCS, etc. IdentityDevice ID Password password that allows the device to join the networkTarget_Device Type Used for Device Discovery, Discovery broadcast ismeant for a certain type of target device. Identity Device IDAddress_Filter IP Subnet filter such that only addresses filteredthrough need to respond; this filter is normally an IP subnet address,e.g. 192.168.3.xx, or a manufacturer- specific MAC address, e.g.00-10-18-XX-XX-XX Filter_Type Type of filter, such as IP address or MACaddress MAC — MAC address of wireless station IP_Addr — IP address ofwireless station QoS priority priority/class given to a specific flow802.11e QoS scheme used by an AP, either EDCF or HCF bitrate max maximumbandwidth (in Kbps) allowed for a specific flow Min minimum bandwidth(in Kbps) allocated to a specific flow burst_size maximum burst size forthe traffic flow key value encryption key for a particular client timetime left (in seconds) of the key IP_Subnet — IP subnet that a wirelessclient may be access VLAN — VLAN that a wireless client is associated toFlow_Stats Byte_Count the number of bytes transmitted for a flowPacket_Count the number of packets transmitted for a flow Drop_Count thenumber of packets discarded for a flow ReMark_Count the number ofpackets remarked for a flow Duration the time duration for the flowstats since the last reset Class_Stats Byte_Count the number of bytestransmitted for a class Packet_Count the number of packets transmittedfor a class Drop_Count the number of packets discarded for a classReMark_Count the number of packets remarked for a class Duration thetime duration of the class stats since the last reset Roaming Current_APidentity of the AP the wireless station is about to disassociate New_APidentity of the AP the wireless station is about to associate ClassifierDA Destination MAC address SA Source MAC address VLAN_ID VLAN ID Src_IPSource IP address to be filter by switch Dest_IP Destination IP addressto be filtered by switch Src_Port Source Port to be filtered by switchDest_Port Destination port to be filtered by switch Protocol Layer IVprotocol (field in Layer III IP header) to be filtered by switch FilterAction Action field when there is an in-profile filter match Out_ActionAction field when there is an out-profile filter match 802.1p 802.1ppriority field to be changed as a result of a filter match DSCP DSCPfield to be changed as a result of a filter match TOS TOS field to bechanged as a result of a filter match

In accordance with an embodiment of the invention, the messagingprotocol may be adapted to discover an access device or client in aWLAN. In this regard, it may be necessary to discover which one or moreof a plurality of access points may be a associated with a clientdevice. In a case where an access device may be within a coverage areaof one or more access points, the whereabouts of a client device may bederived from this discovered access point associations. For example, ina case where access points from three (3) different locations receivestrong signals from a particular client device, but no other accesspoint receives any signal from that particular client device, then theclient device may be located in a zone where coverage for the three (3)access points overlap. An actual location of the client device maysubsequently be decided by, for example, a server, a switch and/or anaccess point, after requesting and receiving various information from atleast one of the three (3) access points. Although the server may be aseparate network entity, it may be coupled to and/or associated with theswitch and/or the access point.

FIG. 4 is a block diagram 400 of an exemplary hybrid wired/wirelessnetwork which may be used to illustrate the discovery of access devicesin accordance with an aspect of the invention. Referring to FIG. 4,there is shown a switch 408, a server 406, access points 404, 414, 424,434, and access devices 410, 440. Access points 404, 414 and 424 haverespective coverage areas 402, 412 and 422. Access device 410 may bepositioned in a location where the coverage areas of access points 404,414 and 424 overlap. In this regard, access device 410 may be located inthe overlapping region of coverage areas 402, 412 and 422. Access device440 may be located in the coverage are 432 of access point 434. Theserver 406 may be associated with a switch and/or an access point andmay be separate from or integrated therein. In an alternative embodimentof the invention, the functions of the server 406 may be integratedwithin an access point and/or a switch, thereby eliminating a need for aseparate server to provide discovery functions.

In operation, server 406 may be adapted to broadcast a device discoverymessage, namely Device_Discovery, to some or all the access points inthe network. For example, server 406 may broadcast a Device_Discovery tothe access points 404, 414, 424 and 434, which may be served by switch408. Based on any signals that the access points 404, 414, 424, 434 mayreceive from access devices in the coverage areas of the access points404, 414, 424 and 434, each access point may respond to theDevice_Discovery request initiated by the server 406. Notwithstanding,the scope of the invention is not limited to sending a Device_Discoverymessage only from the server 406.

The Device_Discovery message may be initiated by, for example, switch408 and/or any one or more of the access points 404, 414, 424, 434. Eachof the access points 404, 414, 424 and 434 may respond with at least anidentity of any access device that may be located within the coveragearea or zone of a particular access point. In this regard, access points404, 414, and 424 may all report access device 410 as being in theircoverage area. Access point 434 may report access device 440 as beingwithin its coverage area. In accordance with an aspect of the invention,the server 406 may broadcast a Device_Discovery.req message to theaccess points 404, 414, 424, 434. Each of the access points 404, 414,424 and 434 may respond with to the Device_Discovery message with aDevice_Device.data message.

Upon receiving the response to the Device_Discovery message, the server406 may send at least one AP_Status message to at least each of theaccess points that may report at least one access device located withinits coverage area. In this regard, server 406 may send an AP_Statusmessage to access points 404, 414, 424 and 434. The access points 404,414, 424, 434 may respond with a AP_Status message, providing moredetailed information related to the access device located within itscoverage zone. In accordance with an aspect of the invention, the server406 may send an AP_Status.req message to some or all of the accesspoints that report at least one access device located within it coveragearea. In this regard, server 406 may send an AP_Status.req message toaccess points 404, 414, 424 and 434. The access points 404, 414, 424,434 may respond to the AP_Status.req with a AP_Status.data message.

FIG. 5 is a high level block diagram of a exemplary message exchangethat may be used to discover an access device in accordance with anaspect of the invention. Referring to FIG. 5, server 502 may send aDevice_Discovery.req message to access point 504. Access point 504 mayrespond with a Device_Discovery.data message. Server 502 may send anAP_Status.req to access point 504. Access point 504 may respond with aAP_Status.data message. The following illustrates exemplary messagingprotocol messages that may be utilized to discover a client device.

Device_Discovery.req

-   -   Transaction_ID: 000123293    -   Target_Device.Type: AP    -   Target_Device.Address_Filter: 192.168.xx.xx    -   Target_Device.Filter_Type: IP    -   Target_Device.Identity: TBD    -   Device_Discovery.data    -   Transaction_ID: 000123293    -   Target_Device.Type: AP    -   Target_Device.Address_Filter: 192.168.xx.xx    -   Target_Device.Filter_Type: IP    -   Target_Device.Identity: AD-1002    -   AP_Status.req    -   Transaction_ID: 000123294    -   Session.Client_MAC: 23.EC.EB.14.1A.51    -   Session.AP_ID: AD-1002    -   Session.Status: TBD    -   Session.Signal: TBD    -   AP_Status.data    -   Transaction_ID: 000123294    -   Session.Client_MAC: 23.EC.EB.14.1A.51    -   Session.AP_ID: AD-1002    -   Session.Status: Associated    -   Session.Signal: 85

In a case where another client device, for example AD-1082, alsoreceives a strong signal from the client device, but the client deviceis not associated with that access point, the AP_Status.data responsemay have the following value:

Transaction_ID: 000123295

Session.Client_MAC: 23.EC.EB.14.1A.51

Session.AP_ID: AD-1082

Session.Status: Not-associated

Session.Signal: 79

In a case where another access point, for example AD-1203, does not getany signal from the client device, the AP_Status.data response may havethe following value:

Transaction_ID: 000123296

Session.Client_MAC: 23.EC.EB.14.1A.51

Session.AP_ID: AD-1203

Session.Status: Not-associated

Session.Signal: 0

In another embodiment of the invention, the server 406 (FIG. 4) mayinitially broadcast at least one Device_Discovery message to all of theaccess points in a particular subnetwork. For illustrative purposes,access points 404, 414 and 424 may be located within IP subnetwork192.168.xx.xx. In this regard, server 406 may broadcast aDevice_Discovery message to the access points 404, 414 and 424 in thesubnet. Each of the access points 404, 414, 424 may respond to theDevice_Discovery message and may all report access device in theircoverage area. In this case, access points 404, 414, 424 may report onlyaccess 410 as being in their coverage area. In accordance with an aspectof the invention, the server 406 may broadcast a Device_Discovery.reqmessage to the access points 404, 414, 424. Each of the access points404, 414, 424 may respond to the Device_Discovery message with aDevice_Discovery.data message.

Responsive to replies associated with the Device_Discovery message, theserver 406 may send individual AP_Status request messages to each accesspoint, for example 404, 414, 424 located within the subnet. TheAP_Status message may be sent only to those access points in thesubnetwork that reported an access device within its coverage area. Inthis regard, server 406 may send an AP_Status message to access points404, 414, and 424. The access points 404, 414, 424 in the subnetwork mayrespond with a AP_Status message, providing more information related tothe access device located within its coverage zone. In accordance withan aspect of the invention, the server 406 may send an AP_Status.reqmessage to at least each of the access points that report at least oneaccess device located within it coverage area. In this regard, server406 may send an AP_Status.req message to access points 404, 414 and 424.The access points 404, 414 and 424 may respond to the AP_Status.req witha AP_Status.data message.

In accordance with another embodiment of the invention, the messagingprotocol may be adapted to discover a client device or access devicewithin a wired portion of a wired/wireless LAN or a wired LAN. Theclient device or access device may be, for example an IP telephone. AnIP telephone and an IP Telephony Gateway (IPTG) may both be messageprotocol-enabled. In this regard, the IP telephone and the IPTG mayexchange messages whenever a client device is first connected to thewired LAN. When the IP telephone is coupled to the wired LAN, the IPtelephone may first acquire an IP address. Subsequently, the IPtelephone may be adapted to send a broadcast message to a subnet of thewired LAN in order to search for the IPTG serving the subnet of thewired LAN. Devices other than the IPTG may ignore the broadcast message.The IPTG may respond with its own client identification. Subsequently,the IP telephone may communicate call processing related messages withthe IPTG.

FIG. 6 is a diagram illustrating an exemplary message exchange forlocating a wired client device using the messaging protocol inaccordance with an embodiment of the invention. In general, the clientdevice 602 may first broadcasts a Device_Discovery message to the IPsubnet of 192.168.xx.xx, in order to locate the serving IPTG 604. Basedon responses associated with the broadcast Device_Discovery message, theIPTG 604 may identify itself with its IP address, for example192.168.12.22. Referring to FIG. 6, the IP telephone client device 602may send a Device_Discovery.req to the IPTG 604. The IPTG 604 mayrespond with a Device_Discovery.data message. The following is anexemplary messaging protocol message that may be utilized for locating awired client device in accordance with an embodiment of the invention.

Device_Discovery.req

-   -   Transaction_ID: 000138293    -   Target_Device.Type: IPTG    -   Target_Device.Address_Filter: 192.168.xx.xx    -   Target_Device.Filter_Type: IP    -   Target_Device.Identity: TBD    -   Device_Discovery.data    -   Transaction_ID: 000138293    -   Target_Device.Type: IPTG    -   Target_Device.Address_Filter: 192.168.xx.xx    -   Target_Device.Filter_Type: IP    -   Target_Device.Identity: 192.168.12.22

In a case where it may be necessary to determine an actual or physicallocation of a wired IP telephone, any switches located between the IPtelephone and the IPTG may be utilized to determine the actual location.In this regard, a client device discovery process may be adapted to havethe capability to identify, for example an edge switch, which may bedirectly connected to the IP phone. Switch information, and/or wiringplan information, may be used to indicate the actual or physicallocation of a jack in which the IP telephone may be plugged. The switchmay include suitable logic and/or software, which may be adapted tofilter at least some or all Device_Discovery messages in a messagingprotocol message and record some or all IP address and/or physical portmappings. The port may be an edge port in a spanning tree state, whichmay indicate that the IP telephone may not be connected to anotherswitch. Accordingly, these records may subsequently be sent to the IPTGwhere it may be stored. Any future query for the physical location ofthat IP telephone may be answered by searching these records andextracting information from the stored records.

FIG. 7 is a block diagram 700 of a server 702 that may be adapted todiscover end-points in accordance with an embodiment of the invention.Referring to FIG. 7, there is shown a processor 704, a broadcaster 706,a requester 708, a sender 710 and a receiver 712. The broadcaster 706,requester 708, sender 710 and receiver 712 may be variously coupled toprocessor 704. The broadcaster 706, requester 708, sender 710 andreceiver 712 may contain suitable logic and/or software that may beadapted to facilitate the discovery of end-points in accordance with theinvention.

The broadcaster 706 may be adapted to broadcast discovery messages to atleast one of a plurality of access points. The receiver 712 may beadapted to receive a response from one or more of the access points. Theresponse may report the presence of at least one access device locatedwithin a coverage area of the access points. The requester 708 may beadapted to request from one of the access points, a status of at leastone access device located within a coverage area of one of the accesspoints. The requester 708 may include a sender 710 adapted to send atleast one status request message to one or more access points withinwhose coverage area the access device may be located.

The receiver 712 may be adapted to receive one or more status replymessages indicating a status of one or more access devices locatedwithin a coverage area of one or more of the access points. Thebroadcaster 706 may be further adapted to broadcast the discoverymessage to only those access points located in a particular subnetwork.The broadcaster 706, requester 708, sender 710 and receiver 712 may bemay not be limited to the server 702, but may be adaptively integratedwithin a switch and/or one of the access points.

In accordance with another embodiment of the invention, dependent on themodulation scheme utilized, one or more of the PLCP frames illustratedin FIG. 1 b, FIG. 1 c, FIG. 1 d and FIG. 1 e may be adapted to containinformation which may be utilized for communication in accordance withvarious embodiments of the invention. Additionally, the PLCP frames maybe adapted to convey information for any one or more of the 801.11a,802.11b and 802.11g modes of operation utilized by access points and/oraccess devices in accordance the embodiments of the invention.

Accordingly, the present invention may be realized in hardware,software, or a combination of hardware and software. The presentinvention may be realized in a centralized fashion in one computersystem, or in a distributed fashion where different elements are spreadacross several interconnected computer systems. Any kind of computersystem or other apparatus adapted for carrying out the methods describedherein is suited. A typical combination of hardware and software may bea general-purpose computer system with a computer program that, whenbeing loaded and executed, controls the computer system such that itcarries out the methods described herein.

The present invention also may be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext means any expression, in any language, code or notation, of aset of instructions intended to cause a system having an informationprocessing capability to perform a particular function either directlyor after either or both of the following: a) conversion to anotherlanguage, code or notation; b) reproduction in a different materialform.

Notwithstanding, the invention and its inventive arrangements disclosedherein may be embodied in other forms without departing from the spiritor essential attributes thereof. Accordingly, reference should be madeto the following claims, rather than to the foregoing specification, asindicating the scope of the invention. In this regard, the descriptionabove is intended by way of example only and is not intended to limitthe present invention in any way, except as set forth in the followingclaims.

While the present invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiment disclosed, but that the present invention willinclude all embodiments falling within the scope of the appended claims.

1. A method for providing communication in a hybrid wired/wireless localarea network, the method comprising: broadcasting, by a network device,a discovery message to a plurality of access points within the hybridwired/wireless local area network; receiving, by the network device,respective responses from said plurality of access points, at least twoof said responses reporting a presence of a particular wireless clientdevice located within respective coverage areas of respective ones ofsaid plurality of access points; and transmitting, by the networkdevice, respective status request messages to said respective ones ofsaid plurality of access points requesting a status of said particularwireless client device to determine a serving access point serving saidparticular wireless client device.
 2. The method according to claim 1,comprising, receiving from said respective ones of said plurality ofaccess points within whose respective coverage areas said particularwireless client device is located, respective status reply messagesindicating respective statuses of said particular wireless clientdevice.
 3. The method according to claim 2, wherein each of said statusreply messages indicates whether said particular wireless client deviceis being served by said respective one of said plurality of accesspoints.
 4. The method according to claim 3, wherein each of said statusreply messages further indicates respective signal strengths ofrespective signals sent between said particular wireless client deviceand said respective ones of said plurality of access points.
 5. Themethod according to claim 4, comprising, determining a location of saidparticular wireless client device using said status reply messages. 6.The method according to claim 2, wherein one or more of the following:said discovery message, said status request messages and said statusreply messages is transmitted utilizing a messaging protocol of a devicecommunication protocol umbrella.
 7. The method according to claim 1,wherein said broadcasting comprises broadcasting said discovery messagefrom one or more of the following: a server, a switch and at leastanother one of said plurality of access points.
 8. The method accordingto claim 7, wherein said broadcasting comprises broadcasting saiddiscovery message only to one or more of said plurality of access pointslocated in a particular subnetwork of said hybrid wired/wireless localarea network, said subnetwork with a particular IP address.
 9. A systemfor providing communication in a hybrid wired/wireless local areanetwork, the system comprising: at least one broadcaster within anetwork device, the at least one broadcaster broadcasts a discoverymessage to a plurality of access points within the hybrid wired/wirelesslocal area network; at least one receiver within the network device, theat least one receiver receives respective responses from said pluralityof access points, at least two of said responses reporting a presence ofa particular wireless client device located within respective coverageareas of respective ones of said plurality of access points; and arequester within the network device, the at least one requestertransmits respective status request messages to said respective ones ofsaid plurality of access points requesting a status of said particularwireless client device to determine a serving access point serving saidparticular wireless client device.
 10. The system according to claim 9,wherein said at least one receiver receives from said respective ones ofsaid plurality of access points within whose respective coverage areassaid particular wireless client device is located, respective statusreply messages indicating respective statuses of said particularwireless client device.
 11. The system according to claim 10, whereineach of said status reply messages indicates whether said particularwireless client device is being served by said respective one of saidplurality of access points.
 12. The system according to claim 11,wherein each of said status reply messages further indicates respectivesignal strengths of respective signals sent between said particularwireless client device and said respective ones of said plurality ofaccess points.
 13. The system according to claim 12, wherein the networkdevice determines a location of said particular wireless client deviceusing said status reply messages.
 14. The system according to claim 10,wherein one or more of the following: said discovery message, saidstatus request messages and said status reply messages is transmittedutilizing a messaging protocol of a device communication protocolumbrella.
 15. The system according to claim 14, wherein said at leastone broadcaster broadcasts said discovery message from one or more ofthe following: a server, a switch and at least another one of saidplurality of access points.
 16. The system according to claim 15,wherein said broadcaster broadcasts said discovery message only to oneor more of said plurality of access points located in a particularsubnetwork of said hybrid wired/wireless local area network, saidsubnetwork with a particular IP address.
 17. A network device forproviding communication in a hybrid wired/wireless local area network,the network device comprising: at least one processor that broadcasts adiscovery message to a plurality of access points within the hybridwired/wireless local area network; said at least one processor receivesrespective responses from said plurality of access points, at least twoof said responses reporting a presence of a particular wireless clientdevice located within respective coverage areas of respective ones ofsaid plurality of access points; and said at least one processortransmits respective status request messages to said respective ones ofsaid plurality of access points requesting a status of said particularwireless client device to determine a serving access point serving saidparticular wireless client device.
 18. The network device according toclaim 17, wherein said at least one processor receives from saidrespective ones of said plurality of access points within whoserespective coverage areas said particular wireless client device islocated, respective status reply messages indicating respective statusesof said particular wireless client device.
 19. The network deviceaccording to claim 18, wherein each of said status reply messagesindicates whether said particular wireless client device is being servedby said respective one of said plurality of access points and furtherindicates respective signal strengths of respective signals sent betweensaid particular wireless client device and said respective ones of saidplurality of access points.
 20. The network device according to claim19, wherein said processor determines a location of said particularwireless client device using said status reply messages.